Apparatus for reducing tubes



Aug. 22, 1939.

. G. ASBECK APPARATUS FOR REDUCING TUBES Original Filed May 10, 1934 A434 ATTORNEY.

Patented Aug.. 22, 1939 UNITED STATES PATENT OFFICE 7 Application May 10, 1934. Serial No. 724,968. Renewed January 7, 1938. In Germany November 11, 1933 1 Claim. (or. 80-11) The passage of tubes through reducing rolls has hitherto resulted in the formation of corners or ridges in the interior of the tubes, which is extremely undesirable. The cross-section of a tube of this kind is illustrated by way of example in Figure 1 of the drawing. These corners or ridges are found as a result of the irregular increases in the thickness of the wall of the tube arising from the eifect on the tube of the spaces or clearances between. the flanks of the adjacent rolls constituting one set of reducing rolls. It is well known that a tube spreads out more or becomes thicker in the region of the said clearances than at the crown of the grooves in the rolls. This efiect is accentuated because for technical reasons the grooves of the reducing rolls must be of semi-oval shape with the major axis of the oval parallel to the axis of the roll.

In the usual method of reducing tubes in known rolling mills in which the planes of revolution of the successive sets of reducing rolls are displaced relatively or staggered with the object of rolling down the external ridges or fins resulting from the passageof the tube through a preceding set of reducing rolls, the planes of revolution of both the even numbered and of the odd numbered sets of reducing rolls are situated in the same angular positions. vThat is to say, whilst all the even numbered sets have the planes of revolution of their rolls lying in the same angular positions and all the odd numbered sets have the planesof revolution of their rolls in the same angular positions, the angular positions of the 'planesof revolution of the rolls in the even and odd numbered sets are displaced from one another. It follows, therefore, owing to the repeated passage of one and the samepart of the tube through-the region of the clearances between the flanks of one series of roll sets, either the even or the oddnumbered, thatirregular increases in the wall thickness of the tube will occur with the resulting formation of interior corners and ridges.

Now, the present invention-relates to a method of reducing tubes by rolls and to reducing rolls or reducing mills for carrying out the method whereby the aforesaid disadvantage is obviated. According to the present invention the tubes on passing through the series of sets of two or more rolls are acted upon by the clearances between the flanks of the adjacent rolls of each set at continually changing placesin its periphery. In this manner the eflect produced by these clearances or spaces is distributed around the entire periphery of the tube and consequently the interior face of the wall of the tube rema ns truly circular.

The advantage'intended by the present invention can be obtained by imparting a rotary movement to the tube during its passage through the rolling mill for example by positioning the rolls obliquely or by rotating the tube by other means, for example by twisting guides.

Instead of this the planes of revolution of the reducing rolls in the successive sets of rolls may be so disposed that the clearances or spaces between the flanks of adjacent rolls constituting one of these sets occur at different angular positions in each set.

This can be efiected in accordance with the invention in a particularly simple manner in universal rolling mills in which each set of rolls generally consists of more than two rolls and in which the shafts of each set of rolls are directly driven from a centrally arranged driving member, for example a hyperbolic gear wheel.

In th drawing, Figure 2 represents diagrammatically the usual arrangement 'for the sepasses are alternately displaced by 90, and it shows aseriesof eight passes each of which is made up of two rolls..

Figure 3 illustrates diagrammatically by way' I arrangement of obliquely positioned rolls which' impart to the tube a rotary movement in addition to a longitudinal movement, each set of rolls being in this example constituted by two rolls only.

I claim: g

In a tube rolling machine, a plurality of roll stands, each stand comprising opposed rollers having substantially semi-circular grooves therein, said roll stands being arranged in pairsdisposed in' a'position with the diameter of the open portion of the'groove of one roller of each pair disposed at a right angle to the diameter of the open portion of the groove of the other rollers of. each pair, and the diametersof the open portion of the grooves of succeeding pairs of roll stands being arranged in progression with the diameter of the first member of each succeeding pair of roll stands arranged at an acute angle with respect to the diameter of the first member of a preceding pair of roll stands.

GUST AV ASBECK.

20 quence of the passes in which the individual 

